Acute stroke is a common and devastating disorder, the 3rd leading cause of death and the leading cause of adult disability in the US. This application to establish a Specialized Program of Translational Research in Acute Stroke Center at UCLA proposes an integrated research/training program to develop innovative therapies for acute ischemic and hemorrhagic stroke. Three research projects are proposed. Project 1, "The MR and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE) Trial," will determine whether diffusion-perfusion MRI can identify patients who will benefit substantially from mechanical embolectomy with the Concentric Clot Retriever device for acute ischemic stroke up to 8 hrs from symptom onset. This study is a multicenter, randomized, controlled phase 2 trial of endovascular clot retrieval versus conventional medical care in 120 patients with large vessel, anterior circulation ischemic stroke 0-8 hrs from onset. Project 2, the "Hemorrhage Evacuation Employing MR-Guided Endoscopic Surgery (HEME-Surgery) Trial," is a phase 2, randomized, controlled, 60 patient trial of magnetic resonance guided endoscopic surgical evacuation vs. medical therapy within 24 h of acute intracerebral hemorrhage. This trial tests an innovative, minimally invasive surgical technique, applied early after onset, utilizing standard and novel clinical measures of outcome. In addition, studies interrogating the fundamental pathophysiology of brain injury in human ICH are proposed delineating differential gene expression, tissue morphometrics, and multimodal MR signatures in the perihematomal region. In Project 3, "Optimizing and Accelerating Prehospital Care of Acute Stroke," 3 inter-related studies will: prospectively validate a novel field measure of stroke severity, the Los Angeles Motor Scale (LAMS); improve dispatcher recognition of stroke by testing a new dispatcher-specific version of the Los Angeles Prehospital Stroke Screen (LAPSS-Dispatch); and demonstrate the feasibility, validity, and impact upon care of paramedic use of a novel, point of care test that assays 5 serum biomarkers to distinguish true stroke from nonstroke in the field. Five Cores will support the Projects: A) Patient Access, B) Blood / Tissue Specimen, C) Biostatistics / Data Management, D) Neuroimaging, E) Career Development.